The most simple tool: use
pdftk.exe, if you are on Windows):
pdftk 10_MB.pdf 100_MB.pdf cat output 110_MB.pdf
This will be a valid PDF. Download pdftk here.
Update: if you want really large (and valid!), non-optimized PDFs, use this command:
pdftk 100MB.pdf 100MB.pdf 100MB.pdf 100MB.pdf 100MB.pdf cat output 500_MB.pdf
or even (if you are on Linux, Unix or Mac OS X):
pdftk $(for i in $(seq 1 100); do echo -n "100MB.pdf "; done) cat output 10_GB.pdf
fsutil file createnew [filename].[extension] [# of bytes]
fallocate -l 10G [filename].[extension]
For those using macOS mkfile might be a good alternative to fallocate or dd
mkfile 100m some100mfile.pdf
reference - https://stackoverflow.com/a/33478049/711401
I had problems using pdftk with the cat parameter had a better success with output.
The following command worked for me:
pdftk file_1.pdf file_1.pdf file_1.pdf file_1.pdf cat output.pdf
Using cat produced the following error:
Error: Unexpected text in page range end, here: output.pdf Exiting. Acceptable keywords, for example: "even" or "odd". To rotate pages, use: "north" "south" "east" "west" "left" "right" or "down" Errors encountered. No output created. Done. Input errors, so no output created.
I created a 172mb PDF is no time at all.
according to http://www.maketecheasier.com/combine-multiple-pdf-files-with-pdftk/ the command should be
pdftk file1.pdf file2.pdf file3.pdf cat output newfile.pdf
note that you should download windows version of pdftk
If you want to generate a file in the Windows, then, please follow the below steps:
Update: The generated file will not be a valid pdf file. It just holds the given size.
If you want a really big valid PDF file, then
It works for me to create a big file (140MB) after some minutes.
Partly it depends on what you are trying to increase the size of... number of pages, number of images, size of a single image. In my experience, the vast bulk (90%+) of any given 'large' PDF file will be the images.
You could try using a pro product like Adobe InDesign to quickly build a large project and export it as a PDF.
Adobe Acrobat Pro has built-in tools to optimize PDF files -- you try using the tools to 'un-optimize' your file. :)
One possibility is, if you are familiar with PDF format:
You get an valid document of any size, entire file will be processed by a reader.
Have you tried using cat to combine the files?
cat 10MB.pdf 10MB.pdf > 20MB.pdf
That should result in a 20MB file.